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Essential Chemistry for IGCSE - Formulae And Equations (Section 2)

1
Which of these are the products when hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH)?
Answer
(B)
H2O and NaCl
2
Which of the following pairs of elements is likely to form an ionic compound?
Answer
(C)
Sodium and Chlorine
3
In the equation 2Mg + O2 -> 2MgO, which substance is being oxidized?
Answer
(A)
Mg
4
What is the chemical symbol for oxygen?
Answer
(A)
O
5
What is a precipitate?
Answer
(A)
A solid formed during a chemical reaction in a solution
6
What is the chemical symbol for calcium?
Answer
(A)
Ca
7
Which of the following is a characteristic of an aqueous solution?
Answer
(D)
Water is the solvent.
8
What is the formula for the sulfate ion?
Answer
(B)
SO42-
9
What does the subscript in a chemical formula represent?
Answer
(B)
The number of atoms of that element in the compound
10
Which of the following statements is correct about balancing chemical equations?
Answer
A
C
D
11
In an ionic equation, what type of compound is usually broken down to show the ions?
Answer
(A)
Ionic compound
12
What does the law of conservation of mass state?
Answer
(A)
Mass is neither created nor destroyed in a chemical reaction.
13
Which of the following is the correct formula for magnesium chloride?
Answer
(B)
MgCl2
14
What are the key features when writing the formula of an ionic compound?
Answer
A
C
15
What is the formula for sodium chloride?
Answer
(C)
NaCl
16
Which term describes a substance that speeds up a reaction without being used up?
Answer
(C)
Catalyst
17
What is the charge on the sodium ion?
Answer
(A)
1+
18
What is the name of the compound with the formula H2SO4?
Answer
(B)
Sulfuric acid
19
What type of equation uses words to describe a chemical reaction?
Answer
(C)
Word equation
20
What is the formula for ammonium nitrate?
Answer
(C)
NH4NO3
21
In a chemical equation, what do the symbols (s), (l), (g), and (aq) represent?
Answer
(A)
State of matter: solid, liquid, gas, and aqueous solution
22
Which of the following compounds are formed through an ionic bond?
Answer
A
C
23
Which of the following correctly shows the formation of water from hydrogen and oxygen?
Answer
(D)
2H2 + O2 -> 2H2O
24
What does the small letter "l" written in parenthesis after the formula of a compound mean?
Answer
(B)
Liquid
25
What is the formula for calcium oxide?
Answer
(A)
CaO
26
What type of formula provides the smallest whole number ratio of atoms in a compound?
Answer
(C)
Empirical Formula
27
Which of the following correctly shows the formula for sodium hydroxide?
Answer
(B)
NaOH
28
What are the reactants in the following equation: 2H2(g) + O2(g) -> 2H2O(l)?
Answer
A
B
29
What is the formula for magnesium oxide?
Answer
(A)
MgO
30
What is the formula of the compound formed by magnesium and oxygen?
Answer
(C)
MgO
31
When balancing an equation, where are the coefficients placed?
Answer
(C)
Before the chemical formulas
32
What is the formula for water?
Answer
(C)
H2O
33
When balancing a chemical equation, what can you change?
Answer
(B)
Coefficients in front of the chemical formula
34
Which of the following is a correct example of a molecular formula?
Answer
(B)
C6H12O6
35
Which of the following is an example of a word equation?
Answer
(B)
Hydrogen + Oxygen -> Water
36
What is the name of the compound whose formula is H2O?
Answer
(B)
Water
37
What is meant by 'conservation of mass' in a chemical reaction?
Answer
(A)
The mass of the products equals the mass of reactants.
38
Which of the following are crucial in balancing a chemical equation?
Answer
A
C
D
39
Which of the following are the products when calcium carbonate decomposes?
Answer
(B)
Calcium Oxide and Carbon Dioxide
40
Which of the following formulas represents calcium chloride?
Answer
(B)
CaCl2
41
What is the formula for Carbon dioxide?
Answer
(B)
CO2
42
What is the name of the compound, NO2?
Answer
(B)
Nitrogen dioxide
43
Which of the following is a common diatomic molecule?
Answer
(C)
Oxygen (O2)
44
Which of the following statements is/are true concerning empirical formula?
Answer
A
B
D
45
What is a substance that speeds up a chemical reaction, but is not consumed in the reaction?
Answer
(C)
A catalyst
46
Which of the following is a correct chemical equation?
Answer
(D)
2Mg + O2 -> 2MgO
47
What is the meaning of the subscript in a chemical formula?
Answer
(B)
The number of atoms of that element
48
Which of the following is the correct formula for aluminum oxide?
Answer
(B)
Al2O3
49
Which of the following is NOT a rule when naming compounds?
Answer
(B)
Use prefixes to denote the number of atoms
50
What is the charge on the chloride ion (Cl-)?
Answer
(B)
1-